frro

Topic: Trivalent Chrome?

Hi!

We are talkning about different types of trivalent Cr-bathes in my company. Anyone that have good experiance in using sulfate- och chloridebased trivalent cr-bathes?

Fredrik

DustinGebhardt

Re: Trivalent Chrome?

I've used both and each has their good points and bad points.


Chloride-based:

Darker color, but easier to run and tends to be somewhat of a thicker deposit.  Cheaper to set-up and operate


Sulfate-based:

Color closer to hex chrome, but still dark.  Can be expensive to set up (if you use the iridium coated titanium anodes).  Thinner deposit, and the bath chemistry can be more sensitive to metallic contamination.

-Dustin Gebhardt, CEF

Advanced Manufacturing/Finishing Engineer

Moen

Sanford, NC

frro

Re: Trivalent Chrome?

How big difference is the colour?

We have alote of chairs and pipes in our production. Makes this a difference in a choice between them?

jimtrottier

Re: Trivalent Chrome?

The color difference is not that great, most people can not tell the difference.

In the chloride bath the secret is to keep your iron levels very low with ion exchange and run your boric a little on the upside.

If you are running tubes you want to have a good post dip to protect the unplated areas  because it does not give the same protection that hex allows.

frro

Re: Trivalent Chrome?

When you are writing about keeping the iron on a low level my question will be how low?

Fredrik

jimtrottier

Re: Trivalent Chrome?

Below 100 ppm and also copper below 10 ppm  but with ion exchange running this is not a problem.  You want to keep copper out of this bath so you should plate your anode bars or at least after you have set your anodes wrap them compleatly with pvc or plastic tape.

                   Jim

frro

Re: Trivalent Chrome?

Thanks for your great answers!

Anything else you can think of that I should think about when we are going to choose between them?

Fredrik

Last edited by frro (05/09/2009 - 08:32 PM)

SFA

Re: Trivalent Chrome?

Tubular steel that has been bent and welded is known for dragout issues in plating baths.  Excessive dragout could take your tight operating parameters to a new level.  Extra counter flowing rinse tanks can help with this.

skelton

Re: Trivalent Chrome?

This is some good feedback, sounds like a few of you know your stuff. You can always respect a good conversation about metal finishing when the words and syllables are easy to understand..... chloride, sulfate, trivalent, hex-, iron, copper......all of these general terms readily available in any "job" or "captive" shop in the U.S.

However, the customer will be the final decision-maker in this process and it is up to you help them like you company's decision. Of course, that is without all that talk about sulfates and chlorides, that is a discussion you need to be having with your chemical supplier. You need to be talking to your customer base with regards to color: light or dark, regarding thickness, corrosion-resistance, and of course, price. 

Have you considered having different samples of each of the types of tri-chrome to use as a "swatch" for appearance samples? You need to be able to show them the hex- vs. the two different tri-'s for comparison. I would consider this first before making a final decision, it is the customer that is ultimately going to like or dislike this new coating appearance.

Kudos to you for reaching out on this topic!! Always implement "best practices" and take care of your plating line and process chemistry, even if in the most general sense, you will always be one step closer to your successes.

Good luck!!

Skelton



Skelton, hOST
FinishingTalkLive
www.finishingtalklive.com

jimtrottier

Re: Trivalent Chrome?

frro,

I do agree with the last post from Paul Skelton,  If this is something you wish to look further into you should contact some of the vendors who supply these baths and have a talk with them. they can tell you what you need to know about setup and maintence.  They will probably take some of your parts and have them plated in their process for you to compare.  It has been my experience to contact two or three so you can compare their products and prices.

Jim

frro

Re: Trivalent Chrome?

Thanks to Skelton and Jim for your good advise.

I have spoken to two different chemical suppliers and they have given me two different answers. One say Chloride and one say Sulfate. They are thinking in two different ways. I will have to talk to a third supplier and see what they say.

Very good point to give them some parts to plate with different Chrome. Then we will see what the big customers say about the difference.